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Title:

Analysis of the effect of temperature changes combined with different alkaline pH on the β-lactoglobulin trypsin hydrolysis pattern using MALDI-TOF-MS/MS

Document type:
Zeitschriftenaufsatz
Author(s):
Cheison, S. C.; Brand, J.; Leeb, E.; Kulozik, U.
Abstract:
Temperature and pH influence the conformation of the whey protein β-lactoglobulin (β-Lg) monomer, dimer, and octamer formation, its denaturation, and solubility. Most hydrolyses have been reported at trypsin (EC 3.4.21.4) optimum conditions (pH 7.8 and 37 C), while the hydrolysate mass spectrometry was largely limited to peptides with <4 kDa. There are few fl reports on trypsin peptide release patterns away from optimum. This work investigated the influence of alkaline (8.65 and 9.5) and conditions (pH 7.8 and 37 C), while the hydrolysate mass spectrometry was largely limited to peptides with <4 kDa. There are few reports on trypsin peptide release patterns away from optimum. This work investigated the in uence of alkaline (8.65 and 9.5) and optimum (7.8) pH at different temperatures (25, 37.5, and 50 C) on β-Lg (7.5%, w/v) hydrolysis. Sample aliquots were drawn out before the addition of trypsin (blank sample) and at various time intervals (15 s to 10 min) thereafter. Matrix-assisted laser before the addition of trypsin (blank sample) and at various time intervals (15 s to 10 min) thereafter. Matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was used to monitor peptide evolution over time with the use of two matrixes:R-cyano-4-hydroxycinnamic acid (HCCA) and 2.5-dihydroxyacetophenone (DHAP). Mass analysis showed that the N- and C-terminals (Lys8-Gly9, Lys100-Lys101, Arg124-Thr125, Lys141-Ala142, and Arg148-Leu149)of β-Lg  were cleaved early (15 s) implying the ease of trypsinolysis at the exposed terminals. Hydrolyses at 25 C and pH 7.8 as well as at fi
Keywords:
Alkaline pH; MALDI-TOF-MS; ß-Lactoglobulin; Trypsin hydrolysis
Journal title:
Journal of Agricultural and Food Chemistry
Year:
2011
Journal volume:
59
Pages contribution:
1572--1581
Fulltext / DOI:
doi:10.1021/jf1039876
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